Realivox Blue by Realitone is a Virtual Instrument Audio Plugin and Soundware (e.g. samples or presets that load into other products) for Windows and Mac OS X. It includes, and is therefore "powered by", Kontakt Player, which functions as a VST Plugin, an Audio Units Plugin, an RTAS Plugin and an AAX Plugin.

Realivox Blue is a solo female singer featuring a word/phrase builder, enabling the user to create their own words or phrases, which Realivox Blue will then sing. 6 vowel sounds and 23 consonant sounds are available.

True sampled legato is also featured, for a smooth sound between notes. There is also a polyphonic legato feature.

Doubles and triples are included on the interface, enabling Realivox Blue to sound like up to three singers at once. Combined with the polyphonic legato feature, a small choir sound can be achieved, all in one instance.